One of the most striking elements of the protests taking place around the country this week have been the signs—signs that warn, signs that rage, signs that joke, signs that manage, wittily, to do a little of each. Whether scrolled on the sides of old Amazon boxes or painted in primary colors on brand-new poster board, signs, as tools of protest, function as visual voices: Shared on Snapchat and Instagram and Facebook and Twitter, and captured by professional photographers who send the images to the wire services, they translate the hums of the throngs into language. On Saturday, and again on Sunday, as crowds gathered to protest President Donald Trump’s executive order restricting immigration from seven Muslim-majority countries, signs once again served as speech. Some of the most common read “NO BAN, NO WALL.” Some insisted that “IMMIGRANTS MAKE AMERICA GREAT.” Some noted that “JESUS WAS A REFUGEE.”

Many others, however, quoted the words of a familiar poem—an idea coined by the Lutheran pastor and theologian, Martin Niemöller, in the years following World War II. “FIRST THEY CAME FOR THE MUSLIMS,” the signs start. They add a new ending to the well-worn lines: “AND WE SAID ‘NOT TODAY.’”

Protesters at Discovery Green Park during Super Bowl events in Houston, Texas, on January 29, 2017 (Trish Badger / Reuters)Protesters at Discovery Green Park during Super Bowl events in Houston, Texas, on January 29, 2017 (Trish Badger / Reuters)Protesters carry signs and chant in Lafayette Park near the White House during a demonstration to denounce President Donald Trump's executive order that bars citizens of seven predominantly Muslim-majority countries from entering the U.S. on Jan. 29, 2017, in Washington. (Alex Brandon / AP)

The specific words of the saying the signs borrowed from vary; the most commonly cited version of Niemöller’s pseudo-poem, however—the one quoted by the United States Holocaust Memorial Museum, as a lyrical manifestation of the evils of political apathy—reads like this:

First they came for the Socialists, and I did not speak out—

Because I was not a Socialist.

Then they came for the Trade Unionists, and I did not speak out—

Because I was not a Trade Unionist.

Then they came for the Jews, and I did not speak out—

Because I was not a Jew.

Then they came for me—and there was no one left to speak for me.

It is a reference to the Holocaust. It is also, however, a warning about the ease with which such an event could occur again, if we of the present allow ourselves to become ignorant of the lessons of the past. Niemöller, born in 1892, was German, and a Protestant. Initially a supporter of Hitler’s rise to power, Niemöller came to oppose him in the years leading up to the war: In 1933, he became the head of a group of opposition clergy members, the Pfarrernotbund, or the Pastors’ Emergency League. For that, in 1937, he was arrested and sent to the concentration camps—first to Sachsenhausen and then to Dachau. He survived until the end of the war, when the Allies liberated him and his fellow prisoners. Niemöller returned, after that, to the clergy—and he focused, for the rest of his life, on reconciliation as both a political and a theological aspiration. “First They Came” emerged from that effort.

Niemöller himself resisted the notion that the lines constitute a poem; instead, he said, their ideas came gradually, and organically, through a series of speeches he delivered after the war. One scholar, UC Santa Barbara’s Harold Marcuse, who has studied Niemöller’s diaries, suggests that “First They Came” might have crystallized during a visit Niemöller took to Dachau in November of 1945, mere months after his liberation from the camp. The quotation itself, as it’s used today, Marcuse notes, “most likely emerged in 1946, and it definitely took on the well-known poetic form by the early 1950s.”

And it quickly became popular, from there, as a lyrical argument for civil rights and collective action—and, more broadly, for simple empathy. The quote was that rarest of things: a political argument grounded in religious tradition. As Niemöller explained of the origin of the lines, in 1976 [translated from the German]:

There were no minutes or copy of what I said, and it may be that I formulated it differently. But the idea was anyhow: The communists, we still let that happen calmly; and the trade unions, we also let that happen; and we even let the Social Democrats happen. All of that was not our affair. The Church did not concern itself with politics at all at that time, and it shouldn’t have anything do with them either. In the Confessing Church we didn’t want to represent any political resistance per se, but we wanted to determine for the Church that that was not right, and that it should not become right in the Church ….

In 1933, Niemöller added, he and his fellow clergy members included in the founding documents of the Pfarrernotbund the idea that any action made against a minister of Jewish heritage would be considered an action against the collective. As he put it: “That was probably the first anti-antisemitic pronouncement coming from the Protestant Church.”

What gives “First They Came” such resonance today, though, isn’t merely its warnings about the dangers of apathy or its recognition of what would later be dubbed “normality creep” or, indeed, its lesson on the ease through which the privileged can become the oppressed. The lines’ elegant structure also encourages—indeed, demands—a subjective interpretation. “First They Came” is uniquely malleable: a 20th-century poem that reads as almost tailor-made for the remix culture of the 21st. It features an almost fill-in-the-blank format, suggesting both hyper-personalization and omni-relevance. It is no surprise, in that sense, that its structure has been adopted by everyone from Angela Davis (“If they come for me in the morning, they will come for you in the night”) to union activists (“First they came for McDonald’s…” *.

“First They Came,” in other words, is particularly attuned to the needs of the modern protest: It offers wisdom about the evils of the past, in an attempt to prevent more evils of the future. To use its language is to claim an understanding of history—and an understanding, too, of how readily its mistakes can be repeated by those who fall victim to the luxuries of forgetfulness. It is #neveragain, and #neverforget, with the subjects added in. It is a poem made powerful by its pronouns: They-I-I, They-I-I, They-I-I, They-no one-me.

Harold Marcuse, for his part, warns that remix was likely not Niemöller’s intention when he used his warnings as a refrain. “Niemöller’s original argument was premised on naming groups he and his audience would instinctively not care about,” Marcuse writes. “When his poem is invoked today it is usuallyto add one’s own group to the list of persecuted. That was not a meaning that Niemöller ever wished to convey.” It’s an objection, however, that could prove the rule: “First They Came,” as used today, derives its power from the notion that no one should be instinctively not cared about—that everyone is deserving of attention and, indeed, protection. That is the nature of politics, and of compassion. And it is to our peril, the poem suggests, that we forget how wound and woven we all are, in the end. They-I-me: The great promise—and the great threat—is, the poem warns, that they will prove to be the same.